What steps will reproduce the problem?
1. Have an older version of LibToast
2. Newer Version is loaded after and upgrade
3. Have an Addon call LibToast over LibSink, where the RegisterSink is the old
4. The call will use the newer version but the setting of internal_call will happen in the old version and the new version will not see it and error out

What version of the product are you using?
Version 9 and 10

Do you have an error log of what happened?
3x Archy\Libs\LibToast-1.0\LibToast-1.0-10.lua:582 LibToast-1.0:Spawn() - template_name must be a non-empty string.
[C]: ?
Toaster\Libs\LibToast-1.0\LibToast-1.0-10.lua:465 in function `func'
Archy\Libs\LibToast-1.0\LibToast-1.0-10.lua:582 in function `func'
Archy\Libs\LibSink-2.0\LibSink-2.0-90097.lua:403 in function <Archy\Libs\LibSink-2.0\LibSink-2.0.lua:389
Archy\Libs\LibSink-2.0\LibSink-2.0-90097.lua:409 in function `Pour'
Rarity\Core.lua:2850 in function `OutputAttempts'
Rarity\Core.lua:1296 in function `CheckNpcInterest'
Rarity\Core.lua:1167 in function `?'
...Ons\Ace3\CallbackHandler-1.0\CallbackHandler-1.0-6.lua:147 in function <...Ons\Ace3\CallbackHandler-1.0\CallbackHandler-1.0.lua:147
[string "safecall Dispatcher[2]"]:4: in function <[string "safecall Dispatcher[2]"]:4>
[C]: ?
[string "safecall Dispatcher[2]"]:13: in function `?'
...Ons\Ace3\CallbackHandler-1.0\CallbackHandler-1.0-6.lua:92 in function `Fire'
Ace3\AceEvent-3.0\AceEvent-3.0-3.lua:120 in function <Ace3\AceEvent-3.0\AceEvent-3.0.lua:119

Locals:
nil